1. Field of the Invention.
This invention pertains to restraining devices, and more particularly to apparatus for restraining large movable objects against a fixed structure.
2. Description of the Prior Art.
Various equipment has been developed to restrain large vehicles such as trucks and trailers against loading docks. Such restraining devices are highly desirable from the safety standpoint, because unrestrained vehicles can roll relative to the dock and thereby render them hazardous to load and unload. Although inexpensive and simple to use, wheel chocks are generally ineffective for restraining a vehicle safely in place. Some prior restraining equipment coacts with a bumper, known as an ICC bar, that is required on most large trucks and semi-trailers. Examples of such equipment include the Powerhook II restraint manufactured by Systems, Inc., of Germantown, Wisconsin. In that design, a large hook is normally recessed in a protected location within the loading dock face. With a trailer at the dock, a hydraulic system operates to extend the hook horizontally under the ICC bar, raise the hook until it contacts the underside of the ICC bar, and then retract the hook horizontally back toward the dock face until the hook engages the ICC bar. Continuous hydraulic pressure maintains a strong force for holding the trailer firmly against the dock. A somewhat similar restraint is manufactured by T & S Equipment Company of Angola, Indiana, under Model No. TL-100. Both of the aforementioned restraint systems are handicapped in that they are mounted within the loading dock foundation. Therefore, retrofit installation after the loading dock has been constructed is difficult and costly.
U.S. Pat. Nos. 4,208,161; 4,281,621; 4,373,847; and 4,553,895 describe manually operated devices for releasably securing a vehicle to an adjacent support by means of the vehicle ICC bar. The devices of those four patents suffer the disadvantage of being able to successfully restrain a vehicle only if the ICC bar is located within a very narrow range of positions relative to the dock. If the ICC bar is outside of that small range, such as through damage, the restraining devices of the foregoing four patents will either be unable to properly engage the ICC bar, or they will allow clearance to exist between the restraining member and the ICC bar through which the vehicle can roll.
The T & S Equipment Company manufactures a Model TL-100-F vehicle restraining device that anchors to the floor of the dock approach. A hydraulic cylinder in a housing actuates a rotating arm and raiseable platform that is engageable with a trailer ICC bar. While that T & S Equipment Company device can accommodate different locations of an ICC bar, it is undesirably expensive and complicated.
U.S. Pat. No. 4,630,989 discloses a power actuated restraint system in which a pivotal bar member can be swung upwardly so as to capture the ICC bar between the pivotal bar member and the loading dock. However, with the system of the 4,630,989 patent, a clearance exists between the ICC bar and the restraint pivotable bar member. The vehicle can roll through that clearance before the bar member actually restrains the vehicle.
Thus, a need exists for a restraining system that accommodates a variety of vehicles to hold them in place without rolling against a stationary structure.